1. Field of the Invention
The present invention relates to a train detection device for railroad models, and more specifically relates to a train detection device that detects such things as the close approach of a train to a crossing and the passage of a train through the crossing in order to activate and deactivate train crossing gates, warning signal devices and the like, and is particularly suited for railroad models in the "HO" and "N" internationally standardized scales. The present invention further relates to a train crossing control apparatus utilizing the above-mentioned detection device.
2. Description of the Prior Art
It is a well-known fact that railroad models have been equipped with crossing gate mechanisms constructed so that when a train passes over a predetermined fixed position on the tracks the crossing gate and the warning signal device are activated, whereupon the gate arms are lowered to block the crossing. After the train has passed through the crossing, the gate arms are raised and the crossing gate and warning signal device are then deactivated. In addition to this basic structure, there exist train sets equipped with three-color warning signal devices which are activated and switched depending on the position of the train on the tracks.
In general, the gate crossing mechanism and the warning signal devices of these kind of railroad models are activated and deactivated by detectors provided on both sides of the crossing at the extremities of a predetermined length of track which defines an activation region for the crossing. In other words, when a train enters into this activation region, its presence is detected by one of the detectors, which then activates both the gate crossing mechanism to close the crossing and the warning signal device to emit a warning signal. Then when the train passes out of the activation region, this is detected by the other detector, which then deactivates the gate crossing mechanism to open up the crossing and shuts off the warning signal device.
At such times, it is extremely important that the train detection device be precise in detecting the presence of the train at close proximity to the crossing and in detecting the passage of the train through the crossing. To accomplish this task it is possible to use two types of detectors, namely, a contact type detector which makes physical contact with the train and a non-contact type detector which does not make physical contact with the train.
As the contact type detector, there is known a microswitch that is provided in a space between the rails of the tracks so as to make contact with the wheels of the train when the train rides over the microswitch, thereby changing the ON/OFF mode of the microswitch.
As for the non-contact type detectors, several arrangements are in general use, such as the provision of a silicon diode in series circuit between the rail and the power supply feeder, which utilizes drops in voltage, or a light sensor comprising an opposing pair of a light-emitting diode placed on one side of the tracks and a light-receiving diode placed on the other side of the tracks. There is also a reflected light type sensor that comprises a light emitting diode provided in the space between the rails to emit light upwardly away from the tracks, a reflector provided on the bottom of the train for reflecting such light, and a light-receiving diode for detecting the reflected light from the reflector.
However, with regards to the contact type detector mentioned above, with each pass of the train, the microswitch gets flicked back and forth between its ON/OFF mode, and this leads to damage of the switch over time. Furthermore, dust and other particles are likely to be accumulated at the contact point of such switch, resulting in poor, and eventually insufficient, contact between the train and such switch. Moreover, there is the added adverse influence upon the control of the operation of the train as a result of the increased resistance arising from the unavoidable mechanical contact of the switch with the wheels of the train.
Now, as for the non-contact type detectors, in the case of the voltage-drop detectors, any change in speed of the train can easily give an adverse effect on the function of the detector. In other words, if the speed of the train is not constant, the detector will be unable to detect the train's approach or passage.
In the case of the light sensor comprising an opposing pair of light-emitting and light-receiving sensors, the presence of these two elements on or in the vicinity of the tracks has a degrading affect on the appearance of the railroad model. Moreover, when the train has a plurality of cars, the spacing between adjacent cars allows the light emitted from the light-emitting diode to reach the light-receiving diode, which results in the sensor being switched back and forth between the ON and OFF modes a multiplicity of times as the train passes by the sensor, making it a very cumbersome method of detecting the passage of the entire train.
With regards to the reflection type sensor, if the reflector gets dirty or scratched, the light reflected therefrom will be irregular, which can give rise to malfunctions. Moreover, the sensor will respond to such things as a cat jumping over the tracks where the sensor is located or a person peering into the the sensor, resulting again in malfunction of the sensor.
In order to remedy the above-mentioned problems, it becomes necessary to implement complex controls that give rise to increased costs, thereby making the railroad model that incorporates such complex controls prohibitively expensive.
Further, even though most railroad models are constructed to allow an operator to change the direction of the electric current supplied to the rails in order to change the direction of motion of the train, in the prior art railroad models mentioned above, various unfavorable outcomes can arise when the direction of motion of the train is changed while the train is still within the crossing gate activation region. For example, if the direction of motion of the train is switched after the train has entered into the activation region but before the train has yet reached the crossing, the crossing gate will still remain closed. Moreover, if the direction of motion of the train is changed just before the train has reached the sensor on the other side of the crossing, the train will pass back through an open crossing.